fix: use strtobool to parse CIBW_PYPA_BUILD

Author: mayeut

cibuildwheel/__main__.py

@@ -26,6 +26,7 @@
     Unbuffered,
     detect_ci_provider,
     resources_dir,
+    strtobool,
 )
 
 
@@ -186,7 +187,7 @@ def main() -> None:
     build_config = os.environ.get("CIBW_BUILD") or "*"
     skip_config = os.environ.get("CIBW_SKIP", "")
     test_skip = os.environ.get("CIBW_TEST_SKIP", "")
-    pypa_build = os.environ.get("CIBW_PYPA_BUILD", "0")
+    pypa_build = strtobool(os.environ.get("CIBW_PYPA_BUILD", "0"))
 
     environment_config = get_option_from_environment(
         "CIBW_ENVIRONMENT", platform=platform, default=""
@@ -329,7 +330,7 @@ def main() -> None:
         environment=environment,
         dependency_constraints=dependency_constraints,
         manylinux_images=manylinux_images,
-        pypa_build=bool(pypa_build),
+        pypa_build=pypa_build,
     )
 
     # Python is buffering by default when running on the CI platforms, giving problems interleaving subprocess call output with unflushed calls to 'print'